This is the larva of a phengodid beetle. It is more commonly called a railroad worm. It is a type of glow worm.
You can learn more about this at the following web site. http://db2.photoresearchers.com/preview/BT0270.html
Thank you to Professor Michael J. Raupp (Department of Entomology at the University of Maryland) for identifying this interesting critter.
photos Hester Burch
Found at the Elms in late September of 2011 and another one in early October 2011.